Radio-frequency (RF) waveguides are used in various applications involving interactions between RF fields and particle beams. One important use of waveguide structures in science and industrial applications is charged particle acceleration. RF resonant cavities are constructed to develop very high electric fields in the gap where the gap field is matched to the speed of the particles. Since the speed of the charged particles is almost equal to or slower than the speed of light, a “slow wave” structure is needed. A regular straight hollow waveguide supports only a “fast wave” whose phase velocity is greater than the speed of light.
Prior slow-wave structures used in accelerating cavity applications have been constructed as multi-cell, disk-loaded structures having corrugations along the beam-axis. These structures generally consist of many small, individually-machined parts which are assembled using expensive welding or brazing processes. Since each cell in the structure must resonate at a specified frequency, each cell must be individually tuned, which is also an expensive and time-consuming process.
What is needed, therefore, is a particle beam accelerating cavity structure which is inexpensive to manufacture and which does not require tuning of individual resonate cell structures.